A/F & O2 sensor reader for Toyota

So, I've had a 420 code on my Toyota for a while. Before, I was using Scotty Kilmer's advice of pouring laquer thinner in the gas tank to clean out the Cat for another 6 to 12 months. That helped me for a few years. But, that hasn't been helping me for the last 3 months. So, I'm hoping to find a tool that will allow me to read the sensors in the Cat system to determine where the problem is. I've read that, instead of 2 oxygen sensors, my car might have an air-fuel sensor upstream and an oxygen sensor downstream. However, it looks like not all ODB2 readers can read one or both sensors. So, does anyone have a lead on an ODB2 reader that can read both the A/F and O2 sensors on a Toyota

I have a 2009 Toyota Camry 2.4L 2362CC 2AZ-FE

Kilmer is a hack. Don't listen to anything he says.

Your car likely has a precat o2 and a post cat o2. The post cat o2, or the cat itself is going to be the one at fault for a P0420. P0420 has to do with catalyst efficiency, and not with the air/fuel mixture.

Correct

Your car likely has a precat o2 and a post cat o2. The post cat o2, or the cat itself is going to be the one at fault for a P0420. P0420 has to do with catalyst efficiency, and not with the air/fuel mixture.

Ok. Well, I managed to take the post cat o2 off and cleaned it with carb cleaner. Not sure if that will do anything. If not, then I guess replacing that will be the next cheapest thing apart from replacing the Cat.